CONTENTS 



Foreword by Fairfield Osborn vii 



Preface xi 



I. Introduction 1 



The Problems 3 



Our Increasing Requirements for Water 10 



The Need to Know What We Are Doing 10 



II. Hydrologic Principles and Basic Data 15 



The Hydrologic Cycle 15 



Inventory of Our Water Resources 18 



The gross water supply: precipitation 20 



The surplus: stream flow 21 



The return to the atmosphere: evapotranspiration 21 



Delineation of Arid and Humid Regions 25 



Nature's Great Reservoirs: Ground Water 27 



Delineation of ground-water reservoirs of the United 



States 29 

 Changes of storage in a ground-water reservoir 32 

 III. Problems Resulting from Ground-water Develop- 

 ment and Use 35 

 Reservoir Problems 36 

 Reservoirs with natural replenishment inadequate 



for current uses 36 

 Perennial overdraft and emptying reservoirs, 37; The com- 

 plication of introducing unusable water, 51; Corrective meas- 

 ures to reduce overdraft, 60. 

 Reservoirs with natural replenishment adequate for 



present uses 77 

 Problems of maximum sustained development 92 

 Pipeline Problems 98 

 Dispersed development remote from recharge areas 101 

 Concentrated draft from a part of a reservoir 109 

 The danger of drawing unusable water into a reser- 

 voir 123 



UM 



